1. Field of the Invention
The present invention relates to image display systems and more particularly to display controllers that interface between a source of image data and a display device.
2. Description of the Related Art
Modern hand-held digital imaging devices include dedicated digital cameras and cell phones, personal digital assistants (PDAs), and other devices incorporating digital imaging functionality. The imaging system in these devices include an image sensor and various electronics to pass the image from the sensor to a display or to memory. Certain imaging modules containing the sensor are capable of operating in one of two modes depending upon whether the image is being sent to the display or the memory.
In a first mode, referred to herein as a preview mode, the imaging module provides a low-resolution image in an uncompressed format which is refreshed several or many times each second. This provides preview image data that may be sent directly to the display for real time previewing of the image being captured by the sensor.
In a second mode, referred to herein as a capture mode, the imaging module provides a higher resolution image in a compressed format. This compressed image data may then be stored by the imaging device in non-volatile memory or transmitted to some remote storage location.
A problem arises that, during the image capture mode, the display ceases receiving preview image data while the higher resolution image is compressed and sent to the memory. Depending upon the resolution of the image, processor and bus speed, and other attributes, this interruption of preview image data can last several seconds. As a result of the interruption of preview image data transmission, the display may freeze or be blanked-out until the preview image data resumes.
This can lead the user to become frustrated while waiting for the resumption of the preview image which can therefore lead to a poor perception of the product. Prior attempts at reducing the interruption of the preview image updates have revolved around increasing the processing power and clock frequency of the system. However, these methods have resulted in poor battery life and extra cost.
Thus, there exists an unmet need to reduce or eliminate the interruption of the preview image data while in the capture mode without negatively impacting the cost, complexity, or battery life of the product.